Multivariate screening analyses of electrochemically driven nutrient recovery from wastewater using nutrient removal and energy consumption as responses

Abstract

Crop production benefits from nutrients in animal wastewater, but direct usage has had an adverse impact on the environment. This impact could be mitigated by electro-precipitation of nutrients from wastewater for recovery as solid fertilizer. However, to recover these nutrients at high rates and minimize energy consumption requires an efficient evaluation of independent variables on these responses. This paper provides these analyses by evaluating the effect of five independent variables – temperature, cathodic potential, turbulence and molar ratios (Mg²⁺:Ca²⁺and N:P) – on phosphorus and nitrogen removal efficiencies and specific energy consumption.

Screening results indicate electrochemical P-removal was most affected by the Mg:Ca ratio, while N-removal was inconclusive due to the experiment duration. The specific energy consumption was most affected by Mg:Ca ratio, temperature and N:P ratio and could be made competitive with industrial routes by controlling these three variables. Overall, for the conditions assessed, struvite formation was most favored at lower temperatures.